Creator of Fox in Sox, The Cat in the Hat and a goo-chewing Goo-goose, you might think you know the great Dr. Seuss.

But you don’t.

There’s another side to Theodor Seuss Geisel — several sides — that dripped from his paintbrush and onto the canvass late at night, alone in his studio, to decompress after long days filled with children’s books, cartooning and advertising work. Reproductions of those paintings and other personal projects of the iconic author and illustrator comprise Dr. Seuss’s Secrets of the Deep at the P&C Art Gallery, 212 King St.

“If the heart of the man was his work in children’s literature, his artworks were his soul,” said Bill Dreyer, the exhibition’s curator. “[The exhibit] really shows you so much about who he is and who he was as a person when you go and look at his artworks.”

"Semi-Normal Green-Lidded Fawn," a three-dimensional "taxidermic" version of a Dr. Seuss character, is priced at $3,495. Geisel's art was influenced by his father, a zoo superintendent who often let Geisel have spare animal parts like antlers after they died. (David Sachs)

Dreyer describes Seuss’s personal collection of paintings and sculptures as “secret art.” Geisel literally kept them in the closet, away from the public eye, and his widow, Audrey Geisel, has never sold an original Seuss. She authorized high-quality lithograph prints so the public can see the ulterior side of her late husband. The printing plates were destroyed immediately afterward.

It’s not as if Dr. Seuss moonlighted as a completely different artist; his personal work was just as surreal as his children’s books, like in “Incidental Music for a New Year’s Party,” a painting of dynamic proportions depicting a scene of raucous musicians and their instruments that define imagination.

Then there’s probably the bawdiest piece Seuss ever painted: “The Rather Odd Myopic Woman Riding Piggyback on one of Helen’s Many Cats.” It’s easily the most sophisticated painting of a cat with a naked woman on its shoulders ever created, taking cues from Picasso, but with a wink-and-nudge that Seuss made famous in his children’s books.

“He was doing this for his own, personal enjoyment, so he didn’t hold back anything,” Dreyer said.

"Cat Behind the Hat, Ted Geisel’s most iconic self-portrait, ran in the July 6, 1957 issue of The Saturday Evening Post. Appearing just four months after the launch of The Cat in the Hat, this classic portrait depicts Dr. Seuss as his mischievous alter ego, complete with red and white stovepipe hat, cat ears, and the Cat’s now famous red bow tie.

Geisell published 44 children’s books under the Seuss pseudonym and changed the way a generation learned to read, putting an end to the Dick and Jane method and replacing it with the zany but intelligent life lessons only teachable by a cat wearing a candy-striped stovepipe hat. Geisell sold 200 million books in his lifetime, but has sold 400 million since he died in 1991, Dreyer said.

“That’s why the exhibit has generated so much interest … you already know so much about Dr. Seuss,” said Laine Kirkhoff, an art consultant at P&C Gallery. “So many people learned how to read because of him. This gives you an opportunity to see his adult personality.”

It’s free to see Dr. Seuss’s Mr. Hyde side, but to own a piece of it will cost between $275 and $7,000, Kirkhoff said.

For P&C owner Peter Nee, holding the exhibit is a business decision with a happy byproduct. He grew up in Hong Kong without Dr. Seuss books but has since learned an appreciation for his genius: a friend of Nee’s has an extensive Andy Warhol collection, but visitors to his home forget about it as soon as they see his assortment of Dr. Seuss pieces.

“I know how influential [Dr. Seuss] was,” Nee said. “As a business person, of course I always seek to represent artwork that people love, that people enjoy, and I’m happy to promote it for the simple fact that people are drawn to it.”

The number of fans Dr. Seuss has amassed over the years is astronomical, and if anything, the Secrets of the Deep exhibit gives each one a new reason to respect his work.

“People love buried treasure, and when artwork is uncovered like this … it’s just such a great story,” Dreyer said.

Dr. Seuss’s Secrets of the Deep runs through December 24 at P&C Art Gallery at 212 King St. in Alexandria and 3108 M St. NW in Washington, D.C.